minor cleanup on some java sources
[skip ci] got better header detection compiling; need to fix up unit tests
Merge branch 'master' into dev

Conflicts:
	src/java/diff_stats_t.java
[skip ci] Merge branch 'master' into dev

Conflicts:
	src/java/diff_stats_t.java
[skip ci] Merge branch 'dev' of github.com:nroza/grey-duck into dev
[skip ci] made headers a set of lines, improving section detection
Merge branch 'master' into dev

bringing in bugfix stupid formatting in the print visitor
got header detection and pair interspersing working, unit tests changed to pass
[skip ci] trying to fix equal files bug, compiles, fails tests
Fixes #3

added _alg.symdiff for SortedSet

changed file_comparison_result and match_these to do the right thing with regard
to symdiffed lines and headers; i.e., treat them as tolerated pairs

changed files unit tests to reflect the increase in tolerated pairs